qemu: Security fix for CVE-2020-29443

Source: Qemu.org
MR: 109315
Type: Security Fix
Disposition: Backport from https://git.qemu.org/?p=qemu.git;a=commit;h=813212288970c39b1800f63e83ac6e96588095c6
ChangeID: c0296e285169cc937cc9758c9d84ac690297ee54
Description:

(From OE-Core rev: 1765005f73303d9857f9fde93efb1cc8534964f1)

Signed-off-by: Armin Kuster <akuster@mvista.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/qemu/qemu.inc

@@ -59,6 +59,7 @@ SRC_URI = "https://download.qemu.org/${BPN}-${PV}.tar.xz \
            file://CVE-2020-25624_1.patch \
            file://CVE-2020-25624_2.patch \
            file://CVE-2020-25625.patch \
+           file://CVE-2020-29443.patch \
            "
 UPSTREAM_CHECK_REGEX = "qemu-(?P<pver>\d+(\.\d+)+)\.tar"
 

meta/recipes-devtools/qemu/qemu/CVE-2020-29443.patch

@@ -0,0 +1,45 @@
+From 813212288970c39b1800f63e83ac6e96588095c6 Mon Sep 17 00:00:00 2001
+From: Paolo Bonzini <pbonzini@redhat.com>
+Date: Tue, 1 Dec 2020 13:09:26 +0100
+Subject: [PATCH] ide: atapi: assert that the buffer pointer is in range
+
+A case was reported where s->io_buffer_index can be out of range.
+The report skimped on the details but it seems to be triggered
+by s->lba == -1 on the READ/READ CD paths (e.g. by sending an
+ATAPI command with LBA = 0xFFFFFFFF).  For now paper over it
+with assertions.  The first one ensures that there is no overflow
+when incrementing s->io_buffer_index, the second checks for the
+buffer overrun.
+
+Note that the buffer overrun is only a read, so I am not sure
+if the assertion failure is actually less harmful than the overrun.
+
+Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
+Message-id: 20201201120926.56559-1-pbonzini@redhat.com
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
+
+Upstream-Status: Backport
+CVE: CVE-2020-29443
+Signed-off-by: Armin Kuster <akuster@mvista.com>
+
+---
+ hw/ide/atapi.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
+index 14a2b0bb2f..e79157863f 100644
+--- a/hw/ide/atapi.c
++++ b/hw/ide/atapi.c
+@@ -276,6 +276,8 @@ void ide_atapi_cmd_reply_end(IDEState *s)
+         s->packet_transfer_size -= size;
+         s->elementary_transfer_size -= size;
+         s->io_buffer_index += size;
++        assert(size <= s->io_buffer_total_len);
++        assert(s->io_buffer_index <= s->io_buffer_total_len);
+ 
+         /* Some adapters process PIO data right away.  In that case, we need
+          * to avoid mutual recursion between ide_transfer_start
+-- 
+2.25.1
+